DE2407660B2 - VULCANIZABLE RUBBER MIXTURES AND THEIR USE - Google Patents

Description

S- 4

or esterified derivatives of polymethylolmelamines using its reaction products with formaldehyde,

in viscous, liquid form so that their hand- These compounds are generally in a

habitation is laborious, and not just in the amount of 0.1 to 10 parts by weight, preferably

Weighing and transporting, but also with 2 to 4 parts by weight, each based on 100 weights

Manufacture of the rubber compound. s important parts of the rubber component.

As a result of extensive investigations, it was found that vulcanizable rubber compound can, in addition to the aforementioned compounds, which contain a methylolmelamine condensate as a component, contain other additives, such as vulcanizing agents, formaldehyde donors, an excellent reinforcing filler or other common additive -Adhesion of rubber with reinforcing agents, io substances or processing aids,
The vulcanizable rubber compounds of the temperature, but also in the case of the compound invention, can be used in a conventional manner, for. B. result under production at high temperature. Use of a roller mill or a Banbury

The subject of the invention are thus vulcanizing mixers, manufactured or processed,

bare rubber mixtures containing a rubber 15 Suitable reinforcing agents are e.g. B. natural

component, resorcinol or a resorcinol form- fibers such as cotton, synthetic fibers such as

aldehyde condensate and compounds based on polyamides, polyvinyl alcohol or polyester, or

contain methylol melamines, which thereby cause steel cord. The fibers can optionally with

are indicated that the methylol melamine from suitable adhesives, such as RFL liquid,

a methylolmelamine trimer to hexamer 20 acts. In the case of steel cord, this can be done with

as the main ingredient. suitable metals, e.g. B. brass or zinc,

Be treated as the condensation of methylol melamines.

The bonding with the vulcanizable rubber is easily carried out by heating under certain conditions can be, this is essential mixture and the reinforcing agents as well as the more advantageous than the etherification or esterification 25 Vulcanization can be carried out in a conventional manner Methylol melamines. In addition, can be guided.

Methylolmelamine condensates obtained by drying in powder The examples and comparative examples explain the deform obtained and are therefore easy to handle invention. All parts and percentages relate to. based on weight, unless otherwise stated. In the case of the rubber used according to the invention, the numerical values in the tables mean components by weight, it can be natural or synthetic parts, unless otherwise stated,
table rubbers, such as polybutadiene, polyisoprene, "" _. ,,,, ·,.
Butadiene-styrene copolymers, acrylonitrile-butadiene production of methylolmelamine copolymers, or mixtures of the aforementioned rubbers equipped with a reflux condenser and stirrer. 35 reaction vessel is charged with 2680 g of commercially available, the invention in the vulcanizable chewing 37% formalin (HCHO: 33 mol), chuk mixture used Mathyiolmelaminkonden- After the pH with about 0.3 ml of 10 N sodium hydroxide are sat by condensation at least one Methyl has been set to a value of 8.5, lolmelamins are added in an aqueous medium at temperatures of 1260 g (10 mol) of melamine and dissolved by ^{heating from 0 to 100 °} C., preferably 50 to 100 ^° C. and 40; then cooled to 60 to in particular 70 to 90 ⁰ C, within a pH Berei- 70 ⁰ C. The reaction solution is prepared by adding a ches 5 to 8 The term "methylol small amount of formic acid to a pH 7-8 with melamine" means here that it is set to melamine and then maintained at 70 to 90 ⁰ C. If one or more methylol- the viscosity of the reaction solution reaches about 40OcP er groups on one or more of the nitrogen atoms 45, about 1.2 ml of 10 η sodium hydroxide solution is added, by which three amino groups are substituted. Examples of adjusting the pH to a value of 10.0. After suitable methylolmelamines are dimethylolmelamine, the reaction solution (358Og) at about 250 ⁰ C trimethylolmelamine, tetramethylolmelamine etc. has been spray-dried, the condensation particles obtained for the production of the methylol through a sieve with a mesh size of melamine condensate is the concentration of the 50 149 μ happened, 1950 g of a white methylolmelamine being obtained in the aqueous medium, preferably powdery reaction product (this is referred to as 5 to 60 percent by weight, in particular 20 to below, as condensate A). The mes-40 weight percent. The control of the pH solution of the degree of condensation by means of the gelper can by adding an organic or inorganic chromatography (GPC) shows that the Lönischen acid, preferably formic acid or 55 solution mainly trimers and tetrameres in acetic acid take place. The condensation will contain a preferred weight ratio of about 1: 2 and that will continue until the viscosity of the no monomeric trimethylolmelamine is present. Reaction mixture 300 to 500 cP, in general Further analytical values are given below, about 400 cP, achieved, with the methylolmelamine condensate obtained as the main component trimers up to 60 C: 34.00%,
Hexamers, preferably trimers or tetramers, of H: 5.00%,
Contains methylol melamine. N: 40.90%,

The methylol melamine condensate is in general methylol groups: 33.5%,

mine used in dry powder form and can contain methylene groups: 5.0%,

in amounts of 0.1 to 10 parts by weight, preferably 65 free formaldehyde: 0.1%.

2 to 4 parts by weight, each per 100 parts by weight of total formaldehyde: 43.2%,

the rubber component. Methylol groups / melamine: 2.22 mol,

The formaldehyde acceptors used are resorcinol or methylene groups / melamine: 0.73 mol.

Production of dimethylol melamine condensates
and tetramethylol melamine condensates

The above procedure is carried out using formalin, corresponding to an amount of 22 resp. 44MoJ HCHO, repeated. Here one obtains

Table I.

Methylolmelamiiikondensite, which is the main ingredient Contain dimethylol melamine or tetramethylol melamine condensates as a dry powder. The so obtained Methylolmelamine condensates are subsequently referred to as condensate B and condensate C. Their analytical values are summarized in Table I.

Monomeric methylol Condensate B one Condensate C melamine Dimethylol Tetramethylol melamine melamine Main condensation 4 to 6 3 to 4 degree (oligomeric degree of sation) Methylol groups (%) 22.7 44.1 Methyl groups ( ⁰ I ₀ ) 6.7 4.2 Total formaldehyde 36.4 51.7 (Vo) Methylol groups / 1.25 3.31 Melamine (mole) Methylene groups / 0.82 0.7 Melamine (mole) N C / o) 49.2 36.1 example 1 raw polyamide co

Six natural rubber compounds are prepared according to Table II on a 25.4 cm roller mill. The resorcinol is incorporated at a roller temperature of 115 ° C, and the other components are mixed in at a roller temperature of 60 ° C. The adhesion of any rubber compound on

Table II

in "India Rubber World", Vol. 114, March, pp. 213 to 219 (1946), described method ("Η test") determined. The vulcanization is conducted for 40 minutes at 140 ^c C. The results are summarized in Table II wherein the values given for the bond

strength mean mean values from 18 test samples each.

component

Attempt no.
1 2

invention

3

Comparative example

Natural rubber

Stearic acid

Highly abrasion-resistant furnace soot

Plasticizing oil

zinc oxide

sulfur

N-Cyclohexylbenzthiazylsulfenamide

Resorcinol

Formaldehyde donor

Condensate A

Condensate C

Tetramethylol melamine dimethyl ether

Trimeihy'olnielamiü

Hexamethylolmelamine hexamethyl ether

Bond strength (Η test: kg)

Example 2

According to Table III, rubber ^{mixtures are mixed at 120 to 130 r} C on a Banbury mixer (Fas-

100 100 100 100 100 100 2 2 2 2 2 2 50 50 50 50 50 50 4th 4th 4th 4th 4th 4th 5 5 5 5 5 5 2.5 2.5 2.5 2.5 2.5 2.5 0.5 0.5 0.5 0.5 0.5 0.5 2.2 2.2 2.2 2.2 2.2 0

2.5

12.3

2.5

12.6

2.5

11.0

2.5

6.3

2.5 7.8

no addition

2.5

capacity 1.8 liters). Vulcanization takes place for 40 minutes at 140 ° C. The adhesion test is carried out in the same way as in Example 1. The results are shown in Table III.

Table III 24 07 660 J 100 8th 11th 12th 7th component 2 50 100 100 Attempt no. 4th 2 2 Natural rubber 7th 8th 9 10 5 50 50 Stearic acid invention Comparative examples 2.5 4th 4th Highly abrasion-resistant furnace soot 100 100 100 0.5 5 5 Plasticizer oil 2 2 2 2.2 2.5 2.5 zinc oxide 50 50 50 0.5 0.5 sulfur 4th 4th 4th 2.2 0 N-Cyclohexylbenzthiazylsulfenamide 5 5 5 Resorcinol 2.5 2.5 2.5 Formaldehyde donor 0.5 0.5 0.5 2.5 Condensate A 2.2 2.2 2.2 . no addition Condensate C Tetramethylol melamine dimethyl ether 2.5 5.2 2.5 Trimethylol melamine 2.5 Hexamethylolmelaminehexamethyl- 2.5 8.5 2.4 ether Bond strength (Η test: kg) 11.8 12.0 7.0

Example 3

According to Table IV are rubber compositions containing as the rubber component of butadiene-styrene rubber, (1.8 liters) prepared in a Banbury mixer at 120 to 13O ⁰ C.

When preparing the mixture, the ingredients are added in the conventional order, with the exception of the formaldehyde donor and the formaldehyde acceptor, which are added at the end will. The rubber mixture is then processed for a further 2 minutes. The total mixing time is 7 minutes.

Table IV

The adhesive strength between the rubber component and a brass-coated steel tire cord (178 × 102 × 0.178 mm) is determined in accordance with ASTM D-2229-1968. The pulling speed is 150 mm / min. The vulcanization takes place for 40 minutes at 150 ^° C.

As can be clearly seen from Table IV, in which the values given for the bond strength represent the mi) 18 test samples mean mean values obtained according to the invention, even during the production of mixtures Achieved excellent adhesion at high temperature using a Banbury mixer.

component

Attempt no.
13 14

invention

15 16

Comparative examples

18th

Butadiene-styrene rubber

Stearic acid

Semi-reinforcing furnace soot

Plasticizer oil

zinc oxide

sulfur

Dibenzothiazyl disulfide

Diphenylguanidine

Resorcinol formaldehyde condensate

Formaldehyde donor

Condensate A

Condensate B

Tetramethylol melamine

Trimethylol melamine dimethyl ether

Tetramethylol melamine tetramethyl ether

Bond strength

100 100 100 100 100 100 1 1 1 1 1 1 70 70 70 70 70 70 10 10 10 10 10 10 5 5 5 5 5 5 2 2 2 2 2 2 1 1 1 1 1 1 0.4 0.4 0.4 0.4 0.4 0.4 3 3 3 3 3 3

2.5

2.5

2.5

175

165

100 130

2.5

115

no addition

90

609508/4

? 631

Example 4

According to table V
under use
same way as

become rubber compounds
of chloroprene rubber in
produced in example 1. the

10

Adhesion strength between the chloroprene rubber mixtures thus obtained and RDL-treated rayon cord (1650 d / 2) is determined in the same way as in Example 1. The vulcanization is conducted for 20 minutes at 140 ⁰ C. The results are summarized in Table V.

Table V

component

Attempt no.

20 21

Er- comparative examples

finding

Polychloroprene 100 100

Semi-reinforcing 30 30 furnace black

Stearic acid 1 1

Paraffin wax 2 2

Magnesium oxide 4 4

Zinc oxide 5 5

Plasticizer 10 10

Diethylthiourea 1 1

Resorcinol 2 2

Formaldehyde donor

Condensate B 1

Hexamethylolmelamine- 1 hexamethyl ether

Bond strength 7 4 (Η test: kg)

100 30

1 2 4 5

10 1 0

no encore

Claims (3)

_, _, Molecule and ether thereof (published JA-PA patent claims: 7 640/72) known; see also the DT-AS 12 98 703 1. Vulcanizable rubber compounds, U.S. Patent No. 13 01475. a rubber component, resorcinol or a These formaldehyde donors, however, have Resorcinol-formaldehyde condensate and compounds 5 different disadvantages, the stickiness in the mix fertilize on the basis of methylolmelamines limit and their practical application difficult contain, characterized, make. So it happens B. with methylolmelamines, that the methylol melamine consists of a methylol such as pentamethylol melamine, tetramethylol melamine melamine trimers to hexamers as main or trimethylolmelamine, very much under the influence of heat component exists. "easy to split off formaldehyde. This means 2. Rubber mixtures according to claim 1, that these compounds to achieve adhesion are characterized in that the methylolmelamine are not very suitable, and not only in the high condensate by condensation of at least one temperature mixture production where formaldehyde-methylolmelamine from the dimethylol group - Acceptors and formaldehyde donors simultaneously melamine, trimethylolmelamine and tetramethylol- 15 with rubber components at high temperatures melamine at temperatures of 0 to 100 ⁰ C and (generally 100 to 12O ⁰ C) in the vicinity of a pH of 5 to 8 in aqueous Medium produced vulcanization temperatures (generally 140 to has been established. 16O ⁰ C) are mixed, but also at the deep- 3. Use of the rubber mixtures after temperature-mixture production, where first form-claim 1 or 2 for connecting reinforcement ao aldehyde acceptors, such as resorcinol with rubber compounds with rubber simultaneously with the components at high temperatures (generally vulcanization. 100 to 12O ⁰ C) are mixed, then one Cooling to 50 to 70 ⁰ C takes place, and then the Mixing in of the methylolmelamines followed by reheating to vulcanization temperatures The invention relates to vulcanizable rubber. Accordingly, these compounds have not found their way into the compounds and their use for compounding practice,
of rubber with reinforcing agents. To the formaldehyde elimination only at higher There are several ways to achieve temperatures in the manufacture of rubber articles Tires, conveyor belts or tubes, in 30 searches, including the etherification or verdene the rubber with reinforcing agents esterification of the methylol groups in methylolmelamines, must be strengthened, establishes the liability between which has been undertaken. The etherification or ver rubber and the reinforcing agents often esterify all or most of the methylol problems represents. groups, however, brings about an excessive increase in In the known methods, the adhesion is 35 temperatures at which the cleavage of the takes place by pretreating the reinforcing agent with formaldehyde, resulting in only a small amount certain adhesives or bonding agents. or no improvement in adhesion at all In recent years, however, a process has been achieved. Attention of the rubber processing indu- Will on the other hand the etherification or strie found in which the adhesion is only partially carried out during the esterification, the production of the rubber mixture is achieved. With improvement of adhesion only in the case of Mischungsder application of this process certain manufacturing at a relatively low temperature of 50 to adhesive during mixing of the different loading are not incorporated 7O ⁰ C in the case of high-temperature Mistandteile in the rubber, whereby the research production reached. It is thus with methylol adhesion between the reinforcing agents and the 45 melamines and their partially etherified or rubber is improved, regardless of whether esterified derivatives have been very difficult to achieve excellent adhesion both in the preparation of the mixture or not. at low temperature as well as at high temperature The term "mixed tack" means that the door can be reached. a measure to achieve adhesion between 50 even when using the partially etherified rubber and reinforcing agents at the same time or esterified derivatives of methylolmelamine !! With the vulcanization by using a, their simultaneous mixing with the form-vulcanizable rubber mixture, which is created by aldehyde acceptors, such as resorcinol and its reaction mixing of the following components, separately or in tion products with formaldehyde, not by high-form of a premix, in a rubber composite - 55 temperature mixing that nente for a solution is obtained: (1) the so-called formaldehyde and uniform dispersion of the acceptors erf order acceptor, z. B. m-disubstituted benzenes (such as Resor- is borrowed because they release formaldehyde at low temperatures, m-aminophenol, m-cresol or m-phenylene doors. For this reason, their only * diamine) and their reaction products with aide- Use in a time-consuming two-stage hyden (such as formaldehyde or acetaldehyde), and 60 process in which the formaldehyde acceptor (2) is the so-called formaldehyde donor, which is initially ^{vulcanized at a high temperature of 100 to 120 0} C with decomposition of formaldehyde. be mixed in and after cooling the cleavage, mix the formaldehyde donors at low) The formaldehyde donors are hexamethylol temperatures of 50 to 70 ° C, whereupon the melamine, hexamethyl ether (known JA-PA 65 heating to vulcanization temperature takes place 16 421/65). Partial ether of hexamethylolmelamine (this is a considerable drop in the technical known JA-PA 27 463/70), Polymethylolmel- efficiency,
amines with no more than 5 methylol groups per, in addition, are most of the more etherified